I ran across this calculator and dc amps to Ac i could never really understand. after studying this and playing with figure entries i finally really understand how dc batteries get drawn down with AC devices-this shows what happens with inverters

This website has been a good source for grasping RV electrical as it is written for the novice. It explains amps, volts and watts and conversions between AC and DC and how to calculate. It also has some bubble diagram charts of how various systems are put together in RVs. It also has some clickable references to other sites.

here's what i don't get... i plugged a small fridge rated at 1.3amps (115v) into my 700 watt inverter in my 2004 RT190P and the inverter couldn't handle it. Why not? 1.3 times 115 is less than 150 watts. So, what am I missing?

That could be a problem with the electronics in the frig not liking the modified sine wave out of your (probably) Tripplite inverter/charger, or the Tripplite kicking off because it didn't like the frig wiring. You might want to get a 500 watt pure sine wave inverter to try. Compressors take a lot of power to start, and depending on what the native power of the frig is, it may have sensitive to dirty power issues.

If it is a compressor fridge, they can draw a lot more than the "rated" current when the compressor starts up- maybe that could be the problem.

I have a couple of small freezers at home that I have converted to fridges for my beer home brewing hobby. I control them with an external thermostat. I measured the current and found that while they barely draw 2 amps when running, they can draw around 13 amps momentarily when the compressor starts up.

The contacts in my external thermostat were only rated for 10 amps - probably that would have been ok, but to be sure, I used a secondary relay in the circuit with 30 amp contacts.

In other words, the thermostat switches the secondary relay which in turn switches on the fridge/freezer.

here's what i don't get... i plugged a small fridge rated at 1.3amps (115v) into my 700 watt inverter in my 2004 RT190P and the inverter couldn't handle it. Why not? 1.3 times 115 is less than 150 watts. So, what am I missing?

That could be a problem with the electronics in the frig not liking the modified sine wave out of your (probably) Tripplite inverter/charger, or the Tripplite kicking off because it didn't like the frig wiring. You might want to get a 500 watt pure sine wave inverter to try. Compressors take a lot of power to start, and depending on what the native power of the frig is, it may have sensitive to dirty power issues.

So, am a little embarrassed to admit but... I was wrong about my inverter being 700w - I checked the specs sheet and it it a 300w pure sine inverter that is installed in my rig. And the fridge having a compressor was clearly too much to for it to run. I think all it was meant to power was the TV and DVD player. So, I'm shopping for a new inverter.